An investigation is underway after a man and woman were found dead inside their Diamond Bar home Thursday.

Authorities said around 9:43 a.m. homicide detectives found the man and woman in the 3300 block of Bent Twig Lane. Both were pronounced dead at the scene.

It was unclear if the Chinese couple were stabbed or shot, but authorities earlier said in a press release that the pair appeared to have been stabbed.

A family member who does not live nearby had contacted a friend to check on the couple's welfare and that's when they were found dead.

Detectives said someone spoke with the victims as early as Wednesday night.

"We're in the process of just trying to figure out how they died, and maybe who wanted them dead - who killed them? If they're having problems with somebody or if somebody was trying to rob them, burglarize the house or what was going on," L.A. County sheriff's Lt. John Corina said.

Authorities said there is evidence of trauma and what may have been a struggle.

The couple were in their late 50s to early 60s and lived alone, but had an at-home art school where they taught every day. Their children are away at college.

Authorities were canvassing the neighborhood looking for surveillance cameras. Corina said it did not appear that the home was broken into or ransacked, but authorities continue to investigate all possible motives.

Anyone with more information about this incident was asked to contact the Los Angeles County Sheriff's Department's Homicide Bureau at (323) 890-5500. Those wishing to remain anonymous may call Crime Stoppers at (800) 222-8477.